1. Field of Invention
This invention relates generally to in-line roller skates, and more particularly to composite wheels for such skates which make it possible to skate at high speed on a skating surface, yet to slow down and stop easily without the need for a brake pad or other special expedients for this purpose.
2. Status of Prior Art
In-line roller skates are often referred to as ROLLERBLADE skates, this being the trademark for the best known brand of such skates. In a skate of this type, each foot of the skater is received in a boot having attached to its underside a frame supporting for rotation a set of wheels in tandem relation. In an in-line roller skate the wheels are aligned in a single row rather than in parallel rows as in a conventional quad roller skate. The in-line wheels are so shaped and placed as to allow tilting of the skate as much as thirty degrees from the vertical without substantially reducing the ground contact area of the wheels.
Using standard in-line roller skates, a skilled skater can attain speeds exceeding 30 miles per hour on a flat pavement, or a wood, asphalt, plastic or other skating surface, a far greater speed than is achievable with conventional quad roller skates. These high speeds make it difficult and sometimes dangerous for the skater to quickly brake, rather than slowly brake, particularly when faced with an unexpected obstacle requiring the skater to come to an abrupt halt to avoid a collision.
According to American Sports Data, in-line roller skating is the fastest growing sport in the United States. As more in-line skaters take to the road, skating-related injuries continue to rise. It is generally recognized that the key to safe in-line roller skating is effective stopping and speed control, and that most accidents occur because of the inability of the skater to brake without losing his balance.
In standard in-line roller skates, mounted at the rear of the right skate is a heel brake provided with a soft rubber pad. To effect stopping, the skater must shift most of his weight onto the non-braking left skate while upwardly tilting the toe of his right skate and pressing the heel brake against the road surface.
This braking maneuver is difficult to execute. As a consequence, inexperienced in-line roller skaters who have difficulty controlling their speed, usually lose their balance when trying to operate the heel brake. These novice skaters may then resort to a crash landing or to spilling onto the grass or dirt on the side of the road. In either case, the skater may suffer broken wrists and arms, fractured shoulders or collar bones, or experience back and ankle sprains.
Many experienced and skillful in-line roller skaters tend not to use the heel brake and, in some instances, they actually detach the brake from the skate. What these skilled skaters do is to use a so-called T-stop maneuver in which the skater drags the wheels of one skate so that it is perpendicular to the other.
The T-stop braking maneuver can wear out a set of wheels in two or three months, depending on the roughness of the road surface. And skaters who frequently brake downhill by using the T-stop maneuver, will find themselves in the need of a new set of wheels in short order. Since a new set of wheels currently costs at least 50 dollars, and in some instances, much more, the T-stop maneuver is one few skaters can afford.
The 1993 patent to Landers, U.S. Pat. No. 5,207,438, calls attention to the drawbacks of existing in-line roller skates having a rear braking pad. As noted in this patent, the brake pad requires the skater to execute an awkward, out-of-balance foot maneuver. Lander's solution to this problem resides in a braking system positioned in the toe portion of the boot. This system includes a rotatable cylinder placed between a pair of brackets, the cylinder rotating in contact with the brackets to produce a frictional force when the cylinder makes contact with the ground.
The 1993 patent to Roberts, U.S. Pat. No. 5,197,572, provides at the rear of an in-line roller skate a cast brake shoe on which a replaceable rubber pad is mounted. Roberts points out that in-line skaters sometimes resort to the same type of action as ice skaters do in stopping forward motion. The same point is made in the 1993 patent to Dettmer, U.S. Pat. No. 5,171,032, who further notes that side slipping, i.e., where ice skates are pointed perpendicularly to the skates direction of movement, would wear flat spots on in-line roller skate wheels which are then rendered unusable.
Thus while Dettmer considers the possibility of using in-line skate wheels to effect braking in the manner of ice skates, he dismisses this maneuver as causing unacceptable wheel wear. Instead, he provided brake pads in the spaces between the wheel and a cable connected to a hand-held lever to actuate the pads.
The 1992 patent to Allison, U.S. Pat. No. 5,135,244, discloses an in-line roller skate having a leaf spring adapted to frictionally engage a forward or rear wheel to impede wheel rotation. The 1993 patent to Hoskin, U.S. Pat. No. 5,183,275, discloses an articulated mounting on an in-line roller skate frame that movably mounts a roller for selective engagement with the rear wheel of the skate and a ground-engaging brake pad arrangement that serves to actuate the mounting to move the roller into contact with the skate wheel and apply a braking force thereto as well as to the skate itself.
Also of background interest is the 1991 patent to Olson U.S. Pat. No. 5,028,058 (assigned to Rollerblade, Inc.) which makes reference to a 1966 patent U.S. Pat. No. 3,287,023 to Ware disclosing an inline skate with thin, rounded wheels adapted to simulate the performance of ice skates. The Ware skate makes use of a wheel formed of firm but slightly soft and resilient rubber, and a toe brake at the front end of the skate to effect stopping.
Our copending patent application discloses in-line roller skates capable of riding at high speed on a skating surface and of being braked by the skater without the need for braking pads or other braking expedients external to the wheels. The wheels included in these in-line skates have a composite structure whose central section is formed in whole or in part from a material having a very low coefficient of sliding friction, the central section being flanked by side sections having a relatively high coefficient of sliding friction.
The relative values of sliding friction are such that when the skates travel in the forward direction, the wheels then roll on the skating surface. But when the skater wishes to slow down or brake, he then angles the wheels of the skates with respect to the direction of forward motion, as he would when braking ice skates, thereby causing the wheels to slide on their central section while the side section frictionally engage the skating surface to slow down the slide to effect a braking action.
Since the present invention resides in a composite wheel, of prior art interest is the Klamer patent U.S. Pat. No. 5,129,702 which discloses a composite wheel for use in an in-line roller skate, a quad roller skate or as a bicycle wheel. The Klamer composite wheel has a central core of hard material and a pair of side wall bodies of soft material flanking the central core. When moving straight ahead, the Klamer wheel rides virtually only on the hard outer surface of the core body. But on curves, the softer side walls contact the ground to provide increased traction and less likelihood of slipping.
The hard, central core of the Klamer wheel is composed of a hard polyurethane which does not have a slippery outer surface and is therefore incapable of sliding on a skating surface, an essential feature of a composite wheel in accordance with the invention.